250 



BOTANICAL GAZETTE 



[APRIL 



been unsuccessful/^ In view of the really large attention that has 

 been devoted to this subject^ it seems surprising that no generalization 

 has been satisfactorily estabhshed (Berg and Gies, I.e.). The 

 affinity of ions for their charges is such a fundamental property that we 

 can hardly conceive of a chemical reaction involving solution in which 

 this affinity or solution-tension^ as some have called it^ does not play a 

 part. On the other hand, there is abundant evidence offered by my 



TABLE XXI: Ethyl acetate 

 Barium^ leady copper, and potassium in contemporaneous test 





COPPER 





m 



Control 



Lnzvme 



Increase 



Water 



0.12 



2.90 



5-70 



0.27 

 2.90 



5-70 



o.iS 



0.00 



128 



64 



0.00 



LEAD 



128 



2. ID 

 4. 20 



2. 10 



4.20 



00 



64 



00 





^^ ■ ^^ ^»-' 



BARIUM 



128 



0.12 



0.12 



0.27 

 0. 27 



0.15 



T C 



64 





\^ . ± ^ 



■ 



POTASSIUil 





128 



,0.12 

 0. 12 



0. 27 

 0. 27 



01=^ 



64 



0.15 





Enzyme o. 10 per cent. Incubation 5 hours at 40 C. 



experiments to show that there is no fixed relation between toxicity 

 and solution-tension to the extent that the toxicity of substances can 

 be exactly estimated from their solution-tension (Pond, /. c. 274)- 



The 



There is difficulty even in agreeing upon a standard of toxicity. 

 minimum lethal dose measures the fatal toxicity, but is it a standard 

 of toxicity ? Does total inhibition measure the toxicity in my o^vn 



experiments ? 

 both mercury 



/16384 and m/s 



lortant 



" The following paper offers a recent and thorough digest of the more imp 

 literature of this subject: Berg, Wm. N, The relation between the physiological actio" 



of ions and their physico-chemical properties. New York Medical Journal for July 

 20 and July 27, 1907. pp. 42. 



